I like Molten Rain , their mana base is not great and it can be good to prevent a Bloodbraid Elf or get the second black mana for Liliana or green mana for Ooze ect
Description Pokmon TCG: Destined Rivals Booster Pack (Team Rocket) - Heroes Take on Team Rocket
Morph on the other hand, is almost exclusively found on creatures, their face down form does not have ward, and their costs can be different than their front face's mana cost
The only creatures that assign combat damage in that step are the remaining attackers and blockers that had neither first strike nor double strike as the first combat damage step began, as well as the remaining attackers and blockers that currently have double strike
Still, its a combination of mechanics we havent explored much
Another door in the House opens, leading into another room that defies all logic and reason